How to access master page div using child page in ASP.NET C#

Hi,

You do not directly access a component of the main page. Its assignatury is of the protected type.

For you access the label component, I suggest that you use public properties in your master page.

HTML code in your master page

<div>
    <asp:Label ID="lblSubHd" runat="server" Text="Um Texto"></asp:Label>
    <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
   
    </asp:ContentPlaceHolder>
</div>

To access the component, here, the code.
Code-behind to master page

public Label MyLabel
{
   get
   {
      return this.lblSubHd;
   }
}

Code-behind to child page

Label mylabelchild = this.Master.MyLabel;

To access the text property of the label component, here, the code.
Code-behind to master page

public string ValueLabel
{
    get
    {
      return this.lblMyLabel.Text;
    }
}

Code-behind to child page

this.MylabelChild.Text = this.Master.ValueLabel;

IMPORTANT! For you use the solution above your child page need to have the master page in asp tag.

<%@ Page Language="C#" AutoEventWireup="true" MasterPageFile="~/Main.Master" CodeBehind="child_page.aspx.cs" Inherits="aplicacao.child_page" %>
<%@ MasterType VirtualPath="~/Main.Master" %>